Development of New LC Chiral Stationary Phases Based on Ruthenium Tris(diimine) Complexes

Enantiopure ruthenium(II) tris(diimine) complexes have been covalently bonded to silica and evaluated as chiral stationary phases for LC. Three binding chemistries were tested and the CSP synthesized by reductive amination of the aldehyde-functionalized silica provided the largest enantioselectivity. The Ru complex bonded CSP showed selectivity toward a variety of racemic compounds. Circular dichroism (CD) detection was used to confirm the enantiomeric separations. This CSP worked especially well for the enantiomeric separation of binaphthyl type compounds in the normal phase mode and appeared to be selective for acidic compounds in the polar organic mode. Effects of mobile phase composition on the enantioseparations were also studied.